On September 9, 2008, Hager made his start on the ECW brand under the ring name Jack Swagger, winning a match against a local wrestler.[16] He quickly made himself a villain when he did not let the referee hold up his arm after the win, and later started a rivalry with Tommy Dreamer by attacking him after Dreamer had saved Chase Stevens from Mike Knox.[17] He later defeated Dreamer in a wrestling match[18] and an "All American Challenge" competition.[19] After weeks of fighting, the two ended their rivalry in an Extreme Rules match, which Swagger won to extend his undefeated streak.[20] He then set his sights on Matt Hardy's ECW Championship, and was named the number one contender on the December 30, 2008 edition of ECW.[21] On the January 13, 2009 episode of ECW, Swagger defeated Hardy to win the ECW Championship, which is his first title in WWE.[22] His undefeated streak in singles matches ended on the February 3 episode of ECW, when he lost to Finlay.

On the March 1 episode of Raw, Swagger beat Santino Marella to wrestle in the Money in the Bank ladder match at WrestleMania XXVI.[23] At WrestleMania, Swagger won the Money in the Bank ladder match, winning a contract for any WWE world championship that he could use at any time over the next year.[24] On the episode of Raw after WrestleMania, Swagger tried to cash in his Money in the Bank contract on John Cena, but changed his mind when he saw that Cena was not hurt enough for Swagger to beat. As the match had never started, Swagger kept the contract for use at a future date.[25]